Caption: Mantis shrimp (Odontodactylus scyllarus). Despite its name this is neither a mantis nor a shrimp, instead being a crustacean only distantly related to the true shrimps. It is an active predator, and uses its club-like front limbs to kill prey. It mainly feeds on crabs and molluscs, breaking open their shells with blows from these clubs. A mantis shrimp strike is one of the fastest animal movements in the world, with a force similar to that of a low-calibre bullet. The eyes of the mantis shrimp are the most complex in the world, containing as many as 16 different types of photoreceptor (compared to four in humans).